PR c++/80891 (#1)

	PR c++/80891 (#1)
	* pt.c (most_specialized_instantiation): Cope with duplicate
	instantiations.

	PR c++/80891 (#1)
	* g++.dg/lookup/pr80891-1.C: New.

From-SVN: r248573

gcc/cp/ChangeLog

 2017-05-29  Nathan Sidwell  <nathan@acm.org>
 
+	PR c++/80891 (#1)
+	* pt.c (most_specialized_instantiation): Cope with duplicate
+	instantiations.
+
 	PR c++/80891 (#3)
 	* cp-tree.h (build_min_nt_call_vec): Declare.
 	* decl.c (build_offset_ref_call_from_tree): Call it.

gcc/cp/pt.c

@@ -21728,6 +21728,7 @@ most_specialized_instantiation (tree templates)
 
   champ = templates;
   for (fn = TREE_CHAIN (templates); fn; fn = TREE_CHAIN (fn))
+    if (TREE_VALUE (champ) != TREE_VALUE (fn))
       {
 	int fate = more_specialized_inst (TREE_VALUE (champ), TREE_VALUE (fn));
 	if (fate == -1)
@@ -21746,13 +21747,13 @@ most_specialized_instantiation (tree templates)
   if (champ)
     /* Now verify that champ is better than everything earlier in the
        instantiation list.  */
-    for (fn = templates; fn != champ; fn = TREE_CHAIN (fn)) {
-      if (more_specialized_inst (TREE_VALUE (champ), TREE_VALUE (fn)) != 1)
+    for (fn = templates; fn != champ; fn = TREE_CHAIN (fn))
+      if (TREE_VALUE (champ) != TREE_VALUE (fn)
+	  && more_specialized_inst (TREE_VALUE (champ), TREE_VALUE (fn)) != 1)
 	{
 	  champ = NULL_TREE;
 	  break;
 	}
-    }
 
   processing_template_decl--;
 

gcc/testsuite/ChangeLog

 2017-05-29  Nathan Sidwell  <nathan@acm.org>
 
+	PR c++/80891 (#1)
+	* g++.dg/lookup/pr80891-1.C: New.
+
 	PR c++/80891 (#3)
 	* g++.dg/lookup/pr80891-3.C: New.
 

gcc/testsuite/g++.dg/lookup/pr80891-1.C

+// PR c++/80891 part 1
+// std::endl is found via two paths and most_specialized_instantiation
+// gets confused.
+
+namespace std {
+  struct A {
+    void operator<<(A(A));
+  };
+  template <typename _CharT, typename _Traits> _CharT endl(_Traits);
+  A a;
+}
+
+using std::endl;
+
+void chi_squared_sample_sized()
+{
+  using namespace std;
+  a << endl;
+}